Quiet wall

ABSTRACT

A folding partition consisting of a pair of acoustical assemblies or sides which combine the acoustical properties of sound absorption and sound transmission loss, and include a flexible blanket of sound absorbent fiberglass sandwiched between an inner vinyl lining and an outer fabric and a plurality of metal panels are attached to the inner side of the vinyl lining. The outer fabric is provided with a multiplicity of perforations for admitting sound into the fiberglass blanket where it is absorbed, while the metal panels further reduce the sound which passes through the fiberglass and further prevent it from passing through the closure.

181/33 GB x 3,234,996 2/1966 King et a1..... 3,223,147 12/1965Holloway.... 1,810,847 6/1931 Nordell et al 2,903,055 9/1959 Merrill2,915,115 12/1959 Reynolds......................

Primary Examiner-Stephen J. Tomsky Assistant Examiner-Stanley A. WalAttorney-Marechal, Biebel, French & Bugg ABSTRACT: A folding partitionconsisting of a pair of 181/33 GB, acoustical assemblies or sides whichcombine the acoustical 160/ 160/ R properties of sound absorption andsound transmission loss, [51] Int. 1504b 1/99, and include a flexibleblankgt of sound absorbent fiberglass 010 1 /0 sandwiched between aninner vinyl lining and an outer fabric [50] 181/33 and a plurality ofmetal panels are attached to the inner side of the vinyl lining. Theouter fabric is provided with a multiplicity of perforations foradmitting sound into the fiberglass blanket where it is absorbed, whilethe metal panels further reduce the sound which passes through thefiberglass and further prevent 160/84 it from passing through theclosure.

Bennett W. Merrill New Castle, Ind. [21] Appl. No. 22,577

Mar. 25,1970 [45] Patented Dec. 21,1971

American Standard Inc. New York, N.Y.

5 Claims, 3 Drawing Figs.

Field of 33 GA; 160/40, 84 R, 84 H; 52/144, 145

11.1mm Cited UNITED STATES PATENTS 3,062,277 11/1962 Merrill UnitedStates Patent [72] inventor [22] Filed [73] Assignee [54] QUIET WALL Mws/ PATENTEB M821 an \62 3a 1:26 sa 6 AL as as r aa INVENTOR 'BENNETT w.MERRILL QUIET WALL BACKGROUND OF THE INVENTION In folding doors orpartitions such as disclosed in U.S. Pat. Nos. 2,903,055 and 3,062,277,which are assigned to the assignee of the present invention, usuallysome form of sound insulation lining is employed to block the passage ofsound from one side of the partition to the other. Commonly, the soundlining is designed to have a relatively high sound transmission loss,and therefore consists of materials which will block the passage ofsound through the partition. Such materials usually have a highcapability of reducing the sound passing through the partition, therebymaintaining a relatively low level of sound on the receiving side (quietside) and a relatively constant level of sound on the source side (loudside). On the source side, the level of sound is influenced-by thesource itself, and also by the sound originated by the source and whichis reflected by the partition back into the source area.

Partition constructions which have a relatively high sound transmissionloss properties also have surfaces which are low in sound absorptionproperties, and therefore reflect a considerable amount of sound energyback into the source room. Constructions of this type have certaindisadvantages. To illustrate, in a school in which this type of foldingclosure is used to separate a classroom or auditorium from a study hall,a high percentage of the noise from the classroom will be reflected backinto the classroom, and its noise level will not be substantiallydiminished. Also, if .there is a constant background noise in the studyhall, such as an air duct or outside noise passing through the window,the sound reflected back into the classroom by the partition may keepthe noise level high enough to pass through the partition and overcomethe background noise in the study hall, so that the sounds from theclassroom will be audible in the study hall.

Moreover, when highly reflective partitions are used to divideauditoriums or large meeting rooms or ballrooms, they create unwantedechoes which are disturbing to the occupants of these areas. And if theyare used in the rear of auditoriums, for example, they will reflect thesound back to the stage area and significantly detract from the clarityof the presentation or performance.

Partitions which have these disadvantages contribute little to anoverall sound conditioning plan. They do not effectively controlenvironmental noise in areas such as auditoriums, classrooms, meetingrooms,- computer rooms, etc. because the critical acousticalrequirement, noninterference with speech communication, is noteffectively controlled. In short, the high percentage of noise reflectedby such partitions causes needless distractions which should not occurwith modern acoustical materials.

SUMMARY OF THE INVENTION The present invention is directed to animproved partition which utilizes the acoustical power of soundabsorption as well as the acoustical property of sound transmissionloss. The invention provides a partition having a construction whicheffectively balances all of the properties which an ideal acousticalpartition should have: high sound absorption, low sound reflection, andlow sound transmission.

In accordance with the preferred embodiment of the invention, a foldingpartition has an acoustical construction which includes a flexibleblanket of sound absorbent fiberglass sandwiched between an inner vinyllining and an outer fabric. A plurality of spaced metal panels areattached to the inner side of the lining adjacent the skeletal frame ofthe partition. The outer fabric has a multiplicity of small perforationsfor admitting a portion of the sound emanating from the source into thefiberglass blanket, so. that it may be absorbed or muffled, while theflexible lining and spaced panels serve to reduce the sound which passesthrough the fiberglass blanket and prevent it from passing through theclosure. Ideally, the wall assemblies of the present invention absorbmore sound than before, so that less sound is reflected.

The basic construction of the present invention may be advantageouslyaltered to suit different acoustical requirements. For example, themetal panels may be used on one side of the closure, or both, dependingupon the expected relative noise levels on each side. Similarly, theperforated fabric and sound absorbing blanket combination may be used ononly one side of the closure, although it is preferred that they be usedon both sides. The present invention enables the architect to achievemany different acoustical environments and make better use of space,simply by varying the constituents of the acoustical construction.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of afolding partition, partly broken-away and partly in fragmentary section,showing the acoustical construction of the present invention mountedthereon:

FIG. 2 is an exploded view of the construction of the invention takengenerally along line 2-2 of FIG. I; and

FIG. 3 is an enlarged sectional view of the assembled parts shown inFIG. 2 and diagrammatically showing the treatment of sound waves by theconstruction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, afoldable closure or partition 10 is shown in fragmentary section andincludes a skeletal frame 11 which extends between a stationary end post(not shown) and a movable end or lead post 12 and is adapted to movealong a rail or track (not shown) by means of ball bearing trolleywheels 13. The frame 11 includes a plurality of crisscrossing top hingeplates 14, which may be constructed according to U.S. Pat. No.3,133,589, assigned to the assignee of the present invention, and acorresponding plurality of crisscrossing bottom hinge plates (not shown)which are pivotally connected to the top hinge plates 14 by a pluralityof vertical rods or pins 15 extending substantially the full height ofthe structure. The pins 15 may be constructed according to thedisclosure of U.S. Pat. No. 3,062,277, also assigned to the assignee ofthe present invention. The skeletal frame ll folds like an accordion atpivot pins l5, and one of the acoustical assemblies 20 of the presentinvention is secured to each side of the frame 11 and is adapted to foldwith it.

The basic construction of the acoustical assembly of the presentinvention, as shown in FIGS. 1-3, includes a flexible blanket 22 ofsound muffling or sound absorbent material, preferably loosely wovenfiberglass or other material which deadens sound, and the flexibleblanket 22 is sandwiched between a flexible inner web or lining 24 and aflexible outer web or cover 26. The web 24 is preferably a strong sheetof vinyl lining material and the web 26 is preferably a vinylcoatedfabric, and both webs extend substantially the full height and width ofthe skeletal frame.

A plurality of vertically elongated metal sound deadening panels 28 arelaminated and spaced in parallel relation on the inner side of thelining 24, preferably by gluing or heat sealing, and extend continuouslythe height of the lining 24. A spring is provided between the panels inthe vicinity of the pins 15 for permitting the flexible components ofthe assembly to fold with the frame. The panels 28 are preferably 22, 24or 26 gauge steel and add mass to the structure for sound transmissionloss and internal reflecting purposes.

As shown in FIGS. 1 and 2, the hinge plates 14 are provided with aseries of holes 30. The metal panels 28 and the inner lining 24 are alsoprovided with holes 32 and 34, respectively, which are aligned with theholes 30 in the hinge plate 14. This arrangement is identical for thebottom portion of the assembly. The holes 32 and 34 may be formed afterthe panels 28 are laminated on the lining 24, if desired, and areadapted to receive steel fasteners 35 and 36 which secure the assemblyto the hinge plates 14.

In the preferred form of the present invention, the other fabric orcover 26 is formed with a multiplicity of small perforations 38 definingan open area of at least about percent of the cover 26. The flexibleblanket 22 is preferably about /1- inch thick and does not span thevertical length of the assembly but rather, as shown in FIG. 2, stopsslightly short of the vertical extremities. This provides room at thetop and bottom extremities of the assembly for sweep strips 40 whichabut the vertical extremities of the blanket 22 and are essentiallyinterposed between the inner lining 24 and the outer fabric 26.

Each sweep strip 40 seals off opposite sides of the room and includes anarrow strip of felt 42 sandwiched between a narrow vinyl strip 46 and awide vinyl strip 48, and the three parts are sewn together along line49. As shown in FIG. 2, the wide strip 48 has a lower end which may beinserted inwardly between the blanket 22 and the outer fabric 26. lltalso has an upper end which extends upwardly above the extremity of theouter fabric 26 and is intended to seal against the ceiling or floor.

A narrow strip of webbing 52 with a plurality of elongated slots 54 issewn to the lower end of the vinyl strip 48 along a line 56. The webbing52 isthen sewn to the outer fabric 26 along a line 58.

In assembling the present invention, the metal panels 28 are laminatedto the inner side of the lining 24 and the lining 24 is secured to thehinge plate 14 of the skeletal frame 11 by means of the fasteners 35.The blanket of fiberglass 22 is then spot glued centrally on the lining24 to leave room on each end for the sweep strips 40. The outer fabric26 with the sweep strips 40 attached through the webbing 52 is thenplaced over the blanket 22 so that the felt strips 42 will abut adjacentthe ends of the blanket 22. The webbing 52 will accordingly lie over theupper and lower extremities of the blanket 22. The outer fabric 26 isthen folded back at line 58, and the fasteners 36 are inserted throughthe slots 54 and the blanket 22, and are secured to the hinge plate 14through the holes in the inner web and metal panels.

In the preferred form of the invention, an acoustical assembly issecured to each side of the skeletal frame 11. The acoustical assemblies20 will accordingly define a central airspace 59 (H6. 3) within theframe 11 which isolates the acoustical assemblies from each other sothat, aside from the hinge plates, there is no direct mechanicalconnection between them. This isolation of the respective sound reducingpanels 28 oneach assembly 20 contributes to the effective soundtransmission loss of the entire closure.

The treatment of sound waves by the basic construction of the presentinvention is diagrammatically illustrated in FIG. 3, which shows theparts in FIG. 2 assembled in overlying relation adjacent the deadairspace 59. Sound waves which emanate from a sound source will strikethe partition and will be separated into essentially threecomponents-reflected sound, absorbed sound, and transmitted sound.Reflected sound is indicated by lines confined to the right of thepartition, marked R; absorbed sound is indicated by lines confinedwithin the partition, marked A; and transmitted sound is indicated bylines within the airspace 59, marked T.

To illustrate the effect of the acoustical partition H0, some soundwaves, such as illustrated by the line 60, will strike the wall and aportion R will be reflected, and a portion T will have sufficientintensity to penetrate through the entire assembly and into the deadairspace 59. But a portion A which is essentially energy will beinternally absorbed by the flexible blanket 22 between the vinyl lining24 and the metal panel 28, and will lower the intensity of the reflectedportion R as well as the intensity of the transmitted portion T. Othersound waves, such as the ones represented by lines 62 and 64, will passthrough a perforation 38, be partially absorbed by the blanket 22, andhave diminished portions reflected from the vinyl lining 2d and themetal panel 28 which may either pass back out through anotherperforation as a reflected portion R or be absorbed when it isinternally reflected back into the blanket by the inner surface of thefabric 26. A small portion of these sound waves may be retransmittedfrom the back side of the metal panels into the dead airspace 59,depending upon their original intensity, Still other sound waves passingthrough a perforation, represented by line 66, will not have sufficientintensity to produce either a reflected portion or a transmittedportion, and will be completely absorbed in the blanket 22. Theforegoing description is intended merely to illustrate the effect of thepresent construction in balancing the transmitted and reflected soundand maximizing the absorption of sound.

Sound waves are essentially compression waves which will work or movethe individual fibers in the fiberglass blanket, and their energy andnoise level are thereby dissipated in the form of heat and movement.Unlike the metal panels which reflect the sound, the fiberglassessentially averages the resonance of the sound by reducing peakwavelengths to a more inaudible form. Thus, the more fiberglass thesound waves are exposed to, the more inaudible they will become.

Accordingly, when a second acoustical assembly is used on the other sideof the partition, it should be apparent that the sound transmittedthrough'the first assembly, which has been substantially attenuated bythe time it reaches the dead airspace 59, will be further reduced, ifnot completely muffled, by the second assembly. In order to pass throughthe partition, such an attenuated sound wave must then pass in thereverse direction through the second assembly. The second blanket offiberglass will therefore absorb a substantial portion of the energy ofthe already deadened sound wave.

There is yet another dampening effect, inherent in the presentconstruction, which further complements the internal reflecting andtrapping effects of the metal panels and lining materials and themuffling effect of the fiberglass blanket. Since the inner lining 24 andthe outer fabric 26 are flexible webs, they will absorb some of thesound energy in the form of heat and will convert it into mechanicalenergy by moving or vibrating. Although the metal panels arestructurally stiff, they also vibrate to some extent when they absorbsound energy. These materials further serve to deaden the transmittedportion of the sound and to provide a more acoustically effectivepartition.

An assembly according to the basic construction of the present inventionwas installed on both sides of a foldable partition and the partitionwas tested according to the American Society of Testing Materials testprocedure C423-66 to determine the sound absorption characteristics.According to this procedure, ratings are determined at six differentfrequencies from c.p.s. through 4,000 c.p.s. The noise reductioncoefficient (NRC) is the numerical average of the four middlefrequencies from 200 c.p.s. through 2,000 c.p.s., and it is the acceptedsingle number rating for an acoustical material. A good grade ofacoustical ceiling tile wall has a NRC of approximately 0.70 to 0.75,while a smooth plaster wall will have a NRC of about 0.02 to 0.03. Thefoldable closure tested with the wall assemblies of the presentinvention was found to have NRC of approximately 0.60. Stateddifferently, of the noise contacting the wall assemblies and ranging inintensity between 200 c.p.s. and 2,000 c.p.s., an average of 60 percentwas absorbed per square foot and an average of 40 percent was reflectedper square foot.

From the drawings and the above description, it is apparent that thebasic construction of the present invention may be varied to alter theabsorption and transmission properties of the partition to suitdifferent acoustical environments. For example, the outer fabric may beperforated on one side of the partition and not on the other. Or, thefiberglass blanket may be used on one side of the partition with orwithout the perforations, or not at all. In places where it is desiredto have a movable wall with acoustical properties, such as in the rearof auditoriums and the like, it is preferred that the highly soundabsorbent perforated cover and fiberglass combination be used on bothsides of the partition. Such a partition substantially eliminates echoesand prevents unwanted sound from being reflected back to the stage. Itprovides properties akin to acoustical title, but in the new and moreusefulform of a movable structure.

Similarly, the metal panels may be eliminated on one or both sides ofthe partition where it is desirable to increase absorption, andwheretransmission of sound through the partition is not altogetherdistracting. For example in open schools where transmission loss isrelatively unimportant, such partitions can be used to form study areasand absorb a high percentage of sound. ln this construction the soundwill pass through the partition without being substantially reflected,and the acoustics in the area will beimproved by the absorption ofenergy as the sound is transmitted through the partition.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of apparatus, and that changes maybe made therein without departing from the scope of the invention, whichis defined in the appended claims.

What is claimed is:

1. In a foldable closure of the type having an accordionlike skeletalframe extending between vertical end posts or the like, an acousticalwall assembly adapted to be mounted on at least one side of saidskeletal frame comprising, an outer web of flexible material, a flexibleblanket of sound absorbing material adjacent the inner side of saidouter web, means defining a multiplicity of perforations in said outerweb for permitting said flexible blanket to absorb sound waves passingthrough the outer web, an inner web of flexible lining material adjacentthe inner side of said flexible blanket, a plurality of sound deadeningpanels arranged in spaced relation along said skeletal frame betweensaid frame and said inner web, and means for securing said assembly tosaid skeletal frame, said assembly providing a significant increase inthe absorption of sound by said closure and a high degree of soundtransmission loss properties of said closure.

2. in a foldable closure of the type having an accordionlike skeletalframe extending between vertical end posts or the like, an acousticalwall assembly adapted to be mounted on at least one side of saidskeletal frame, comprising an inner web of flexible lining material, anouter web of flexible fabric material, a flexible blanket of soundabsorbent material sandwiched between said inner and outer webs, aplurality of metal panels laminated in spaced relation along saidskeletal frame on the side of said inner web facing said frame, meansfor securing said assembly to said frame, and means defining amultiplicity of small perforations in said outer web opposite saidblanket for admitting sound waves into said blanket for absorptionthereby to significantly increase the absorption of sound and thetransmission loss properties of said closure.

3. A foldable closure comprising a skeletal frame, at least oneacoustical wall assembly, means securing said assembly to at least oneside of said frame, said wall assembly being particularly adapted todissipate the energy and decrease the intensity of sound waves strikingsaid closure, including means defining spaced-apart and inner and outerwebs for converting a portion of the sound energy of said waves intomechanical vibration energy, means defining sound absorbent materialbetween said webs for reducing the intensity of another portion of thesound energy of said waves to a more inaudible form, means in said outerweb defining a multiplicity of perforations for admitting sound wavesinto said sound absorbent material and for reducing the number of soundwaves reflected by said closure, and means defining a plurality of sounddeadening rigid panels adjacent said inner web and positioned along saidskeletal frame inwardly of said absorbent material for internallyreflecting the sound waves passing through said perforations and saidmaterial back into said material and for cooperating with said webs totrap internally reflected waves within said assembly to attenuatefurther the intensity of said waves and provide a significant increasein the sound absorption and the sound transmission loss properties ofsaid closure.

8. The foldable closure of claim 3 wherein one of said acoustical wallassemblies is secured to each side of said frame.

5. The closure of claim 3 in which said sound absorbent materialcomprises a blanket of fiberglass.

* IF I! k @2 3 I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3,628 6 Dated December 21, 1971 Inventor( Bennett W. MerrillIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Col. 1, line 56, "power" should be .-property-.

Col. 4, line 6, "in" should be -by-.

Col. 6, line 17, delete "and" following spaced apart.

Signed and sealed this 29th day of August 1972..

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents my UNITED STATES PATENT owicn CERTIFICATE 0i QQRREUMUN PatentNQ- 3,628 ,626 Dated December 21, 1971 Inventor(s) Bennett W. Merrill Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

In the Title:

Cancel "QUIET WALL" and insert -ACOUSTICAL WALL FOR FOLDABLE CLOSURESigned and sealed this 6th day of March 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCI-IALK Attesting Officer Commissionerof Patents

1. In a foldable closure of the type having an accordionlike skeletalframe extending between vertical end posts or the like, an acousticalwall assembly adapted to be mounted on at least one side of saidskeletal frame comprising, an outer web of flexible material, a flexibleblanket of sound absorbing material adjacent the inner side of saidouter web, means defining a multiplicity of perforations in said outerweb for permitting said flexible blanket to absorb sound waves passingthrough the outer web, an inner web of flexible lining material adjacentthe inner side of said flexible blanket, a plurality of sound deadeningpanels arranged in spaced relation along said skeletal frame betweensaid frame and said inner web, and means for securing said assembly tosaid skeletal frame, said assembly providing a significant increase inthe absorption of sound by said closurE and a high degree of soundtransmission loss properties of said closure.
 2. In a foldable closureof the type having an accordionlike skeletal frame extending betweenvertical end posts or the like, an acoustical wall assembly adapted tobe mounted on at least one side of said skeletal frame, comprising aninner web of flexible lining material, an outer web of flexible fabricmaterial, a flexible blanket of sound absorbent material sandwichedbetween said inner and outer webs, a plurality of metal panels laminatedin spaced relation along said skeletal frame on the side of said innerweb facing said frame, means for securing said assembly to said frame,and means defining a multiplicity of small perforations in said outerweb opposite said blanket for admitting sound waves into said blanketfor absorption thereby to significantly increase the absorption of soundand the transmission loss properties of said closure.
 3. A foldableclosure comprising a skeletal frame, at least one acoustical wallassembly, means securing said assembly to at least one side of saidframe, said wall assembly being particularly adapted to dissipate theenergy and decrease the intensity of sound waves striking said closure,including means defining spaced-apart and inner and outer webs forconverting a portion of the sound energy of said waves into mechanicalvibration energy, means defining sound absorbent material between saidwebs for reducing the intensity of another portion of the sound energyof said waves to a more inaudible form, means in said outer web defininga multiplicity of perforations for admitting sound waves into said soundabsorbent material and for reducing the number of sound waves reflectedby said closure, and means defining a plurality of sound deadening rigidpanels adjacent said inner web and positioned along said skeletal frameinwardly of said absorbent material for internally reflecting the soundwaves passing through said perforations and said material back into saidmaterial and for cooperating with said webs to trap internally reflectedwaves within said assembly to attenuate further the intensity of saidwaves and provide a significant increase in the sound absorption and thesound transmission loss properties of said closure.
 4. The foldableclosure of claim 3 wherein one of said acoustical wall assemblies issecured to each side of said frame.
 5. The closure of claim 3 in whichsaid sound absorbent material comprises a blanket of fiberglass.